Electroluminescence (EL) is an optical and electrical phenomenon where a material emits light in response to an electric current passing through it, or in response to being positioned within a strong electric field. Electroluminescent Displays (ELDs) are a type of display formed by sandwiching a layer of electroluminescent material, such as a phosphor based compound, between two layers of electrical conductors, or electrodes. When voltage is applied across the conductors, the layer of electroluminescent material emits radiation in the form of visible light.
Conventional ELDs are made of a first layer of flat, opaque electrodes formed on an insulating substrate. A layer of electroluminescent material is formed on the first electrode layer. A second layer of electrodes is formed over the electroluminescent material with the electrodes of the second layer selectively aligned with electrodes of the second layer. The second layer of electrodes is transparent in order to see light emitted from the underlying electroluminescent material. The insulating substrate is typically PET (polyethylene terephthalate) or glass, and the electroluminescent material is ITO (indium tin oxide). Such ELDs are expensive, substantially rigid, and non-stretchable.